CHAPTER IV 

 The Ultimate Constitution of Matter 



IN chemistry more than in any other branch of Natural 

 Science it is possible to draw a marked distinction between 

 the work of the laboratory and the work of the study 

 between manipulation and philosophical thought. Two 

 lines of research stretch to the chemist's mental horizon. 

 He may either devote the chief part of his time to investi- 

 gating the properties of substances, or he may reason as 

 to the relation between substances and their properties, 

 and devise experiments to check his hypotheses. He is 

 in charge of the matter of the universe. It is, in the first 

 place, his business to prepare all the substances which 

 can exist in a pure, homogeneous or isolated stale, and to 

 investigate their behaviour in relation to one another. He 

 separates matter as it is found in nature into its elements. 

 He forms every combination of the elements which under 

 any conditions can exist as homogeneous bodies as 

 bodies, that is to say, the properties of which are invari- 

 able and uniform throughout their whole mass. That the 

 substance with which he is dealing is partially or com- 

 pletely decomposed during many of his manipulations 

 that, for example, a salt when dissolved has not the same 

 homogeneity which it exhibited in its crystalline form before 

 he dropped it into the water that it is partially resolved 

 by the water into its "ions" does not affect the final 

 result, profoundly as it modifies the action of this salt 

 upon other salts in the same solution. The chemist recog- 



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